Acrylonitrile-butadiene-styrene (ABS)/polyester blends can have good machinability (workability) and excellent physical properties, such as high impact strength. Accordingly, ABS/polyester blends have been widely used in a variety of applications, including the production of internal or external parts of electric/electronic goods and office equipment. However, ABS/polyester blends can burn when used in heat-emitting devices since ABS/polyester blends are combustible. Further, these blends can operate as an energy source to help combustion if ignited by a flame from an external heat source. For these reasons, legal regulations in many countries, including the United States and the European Union, require that resins used in internal and external components for electric and electronic appliances meet flame resistance standards.
There are many methods for imparting flame retardancy to an ABS copolymer resin. In one widely used method for imparting flame retardancy (which can be referred to as an “addition-type flame retardant method”), an organic compound including halogen atoms, such as bromine or chlorine atoms (called a flame retardant) and an inorganic antimony oxide compound, such as powder antimony trioxide or antimony pentoxide (called a flame retardant aid) is added to a powder-type ABS resin. The mixture can be mechanically mixed by a mixer and extruded thereafter. The flame retardant aid is generally a powder antimony trioxide, which can have excellent flame retardant effects.
Antimony trioxide, which is a white inorganic powder, can have an average particle size of about 0.5 to about 2 microns and therefore it can function as a white pigment when added to the ABS resin. Accordingly, it can be difficult to develop color tones, such as primary colors, with an ABS resin that includes antimony trioxide. In addition, the impact resistance or the mechanical strength thereof can deteriorate.
Thus, it is important to minimize adverse effects such as the deterioration of heat stability, physical properties, machinability (workability) and weather stability, while also maintaining excellent flame retardancy when preparing a flame retardant resin.
Korean Patent Application No. 2003-0056039 recites a technology for preparing a flame retardant ABS resin having excellent color tone by combining a bromide bisphenol A epoxy flame retardant and a flame retardant aid such as antimony pentoxide to an ABS thermoplastic resin. Although an ABS resin including antimony pentoxide can have excellent color tone, the flame retardant effect thereof may be somewhat insufficient compared with antimony trioxide, and therefore it can be essential to add an excessive amount of antimony pentoxide to the resin to achieve flame retardancy. Adding too much antimony pentoxide, however, can deteriorate physical properties of the flame retardant resin, such as impact resistance.